It would seem that this "crack" could simply be circumvented by using an alphanumeric password and/or setting the iPhone to shred its crypto key after 10 consecutive password failures. Obviously, neither of these are standard features, but both are available.
> setting the iPhone to shred its crypto key after 10 consecutive password failures
This seems to do decryption on its own, so this setting wouldn't have an effect. If you have the data sitting there and have the encrypted key, there's nothing stopping you from directly decrypting the key with every possible passcode and checking it for validity.
